When summoning mobs with the /summon command like this:
/summon MobName ~ ~ ~ {Attributes:[

]}
different things happen.

Mobs who ignore it:
Bats
LavaSlimes
EnderDragons
Guardians
Ghasts
Squids (if in water)

Mobs who will swim up in water:
Cows
Pigs
Sheeps
Mushrooms
Villagers
Wolfs
Pigmen
Creepers
Skeletons
Witches
Zombies
Rabbits
Endermen (if invulnerable)

Withers will slowly come down to ground if flying.

All the other mobs behave as expected: they don't move at all.